Conventionally, a variety of techniques relating to shift registers for scanning gate lines in a display panel have been proposed.
For example, Japanese patent publication No. 2014-71451 (hereinafter referred to as JP 2014-71451 A) discloses a liquid crystal display device in which a gate driving unit for switching each of the odd-number-th gate lines to a selected state, and a gate driving unit for switching each of the even-number-th gate line to a selected state, are provided in right and left frame regions, which are on both sides of ends of gate lines, respectively. In this liquid crystal display device, a discharge circuit for switching each of the odd-number-th gate lines to a non-selected state, and a discharge circuit for switching each of the even-number-th gate lines to a non-selected state, are arranged in the right and left frame regions, respectively. In this liquid crystal display device, in order to allow stable pixel charging to be performed during the data voltage application, a pre-charging period is provided; in the pre-charging period, a period while a gate driving voltage applied to a gate line is a gate high voltage overlaps with an identical period for another gate line adjacent thereto.
Each discharge circuit in JP 2014-71451 A includes a gate electrode that is connected with a driving unit that outputs a gate high voltage at the end of the gate line selection period, a first electrode that is connected with the gate line, and a second electrode to which a gate low voltage VGL is supplied. The discharge circuit is driven at the end of the selection period in which the gate line corresponding thereto is selected, outputs the gate low voltage VGL to the corresponding gate line, and switches the gate line to a non-selected state.